After undergoing an exercise stress test to determine appropriateness for this study, as well as to determine maximal physiological responses, fifteen males and fifteen females, age 20-40 years, will participate in this study to compare the peak cardiovascular responses to concentric versus eccentric exercise on the Biodex isokinetic dynamometer. Concentric exercise on the Biodex involves extension and flexion of a joint against the resistance of the torque arm, and eccentric exercise involves resisting the force of the torque arm aimed at extending and flexing a joint. Heart rate, blood pressure, rate-pressure product, and electrocardiogram (ECG) data will be collected during and immediately after the exercise. Maximal concentric and eccentric contractions of the quadriceps and hamstring muscles of the subject's dominant leg will be performed during one testing session on the Biodex at speeds of 60, 90, and 120 degrees per second (degrees/s) and 90, 120, and 180 degrees/s for eccentric and concentric modes, respectively with 30 second rest periods between sets and 30 minutes rest in between modes. Results will be analyzed to determine differences in the peak cardiovascular parameters between concentric and eccentric exercise. The results of this study will provide physical therapists with an understanding of how exercise on isokinetic devices affects the cardiovascular system so they can design appropriate and safe exercise regimens.